Process for producing regenerated cellulose particles with encapsulated opacifying or colored bodies



y 28, 1954 G. H. HOLOUBEK ETAL 3,142,580

PROCESS FOR PRODUCING REGENERATED CELLULOSE PARTICLES WITH ENCAPSULATEDOPACIFYING 0R COLORED BODIES Original Filed April 4, 1960 H FIG.5

25 6 22 22 22 FIG 8 32 i1 s 24 "0111104 23 INVENTORS: GEORGE H. HOLOUBEKHARLAND HARMS KENNETH E. GLIDDEN THEODORE SMITH UJ ZT Q UQ BY 1 w ATT'YSUnited States Patent This invention, in general, relates to processesfor producing regenerated cellulose pellicles, foils, tubes, bands andthe like containing finely-divided, opaque bodies encapsulated on saidpellicles, foils, tubes, bands and the like of regenerated cellulose bya covering film of regenerated cellulose. One aspect of the inventionrelates to processes to produce regenerated cellulose gel pellicles intubular or band form which have a metallic luster when dry. Anotheraspect of the invention relates to the production of gel regeneratedpellicles having a printed design, legend, or other indicia with ametallic luster. A still further aspect of the invention is theprovision of processes for applying and encapsulating small, opaquebodies on gel regenerated cellulose films to enhance the appearance ofdry cellulosic films.

This application is a division of our copending application, Serial No.19,923, filed April 4, 1960, now abandoned.

Shrinkable, hollow pellicle closures of regenerated cellulose, such astubular bands and cup-shaped closures, have been used for a number ofyears as secondary container closures or bands about the necks ofbottles. These closures or bands have both a decorative and utilitarianfunction. While providing an attractive decoration for the bottle, theseclosures or bands, when secured about the neck of the bottle and thestopper or closure therefor, serve as a deterrent to tampering with thebottle contents. By pigmentation and/ or printing, these caps or bandscan provide a wide variety of decorative designs or printed matter, aswell as an attractively colored article.

When the shrinkable band or secondary closure of regenerated cellulosein gel form is placed over the bottle top with the primary closure, suchas a stopper or cap, and is allowed to dry, the regenerated celluloseclosure or band shrinks. The shrinkage provides a very firm fit aboutthe bottle neck and primary closure-forming a tightly-stretched, toughseal.

The principal method in use today in the manufacture of regeneratedcellulose bands of the type heretofore described, is by the extrusion ofcontinuous lengths of cellulose tubing regenerated from viscose. Thecontinuous lengths of cellulose tubing are then cut into short lengthsto provide the bands. The bands are packaged and sold to the users ingel form.

Regenerated cellulose produced by the viscose process is usually madefrom wood as the primary raw material. In a typical viscose process,Wood is shipped into small pieces, and the chips are treated with abisulfite salt such as calcium bisulfite. The treated chips are thencooked with steam under pressure for about 14 hours. This treatment doesnot greatly affect the cellulose, but it decomposes and solubilizes theencrusting substancesthus purifying the cellulose. The purified pulp isthen bleached with hypochlorite and converted into paperboard. Afterconditioning the paperboard under definite humidity and temperatureconditions, the sheets are stacked in a press and soaked with a strongsolution of caustic soda (about 18% strength) from one to four hours.This process is known as steeping or mercerizing. The hemicellulose isClaims.

"ice

dissolved in the caustic soda; the cellulose itself is swollen but notdissolved.

After the excess alkali is pressed out of the alkali cellulose, themoist mass is put through a shredding machine where it is broken up intofine crumbs." After shredding the crumbs are aged in contact with theatmosphere. Through oxidation by the atmospheric oxygen, degradativechanges set in. Some depolymerization of the glucose residue in thecellulose molecule occurs, and the degree of polymerization falls fromabout 800 to 350 glucose residues per cellulose molecule. One processcombines the shredding and aging steps by careful control of temperatureand other physical conditions.

After aging, the alkali cellulose crumbs are introduced into rotatingair-tight churns. About 10% of their weight of carbon disulfide isadded, and the crumbs and disulfide are churned up together. A deeporange gelatinous mass of sodium cellulose xanthogenate is formed.Churning is continued for several hours, and thereafter the sodiumcellulose xanthogenate is stirred with dilute caustic soda solution forseveral additional hours at low temperature. The xanthogenate dissolvesto a viscous liquid similar in appearance to honey. This liquid is knownas viscose, but it must be treated further before it is ready forextruding. The viscose contains in the vicinity of 55-70% alkali and6.58.5% cellulose.

The viscose then is agitated in a secondary mixer or blender. Anyundissolved fibers from the original wood pulp are removed by filteringthe viscose.

The viscose solution is next ripened for several days at lowtemperature. During the ripening, the viscosity first falls and thenrises so that by the time the solution is ready for extruding theviscosity has risen almost to its original value. When the viscosesolution is ripe all air bubbles are removed by exposure of the solutionto vacuum.

The viscose solution is extruded in tubular form into an acid bathwherein the cellulose in the viscose solution is regenerated. Sulfuricacid is the acid used primarily for reasons of economics. The bath mayalso contain sodium sulfate, Zinc sulfate and other known modifyingagents.

The reaction of cellulose and caustic to give alkali cellulose isusually expressed:

( 0 10 5)]; nNaOH 8 D0N ')u nHzO Cellulose Alkali cellulose The reactionbetween the alkali cellulose and carbon disulfide may be represented:

(Cu sO4ON2Ju 12082 CGH004OC SNa n Alkali cellulose Alkali cellulosexanthate During the ripening period, some of the alkali cellulosexanthate decomposes, regenerating cellulose which is maintained inemulsion form by the portion of alkali cellulose xanthate stillundecomposed. The conversion of the remainder of alkali cellulosexanthate to cellulose is accomplished in the acid bath. The latterreaction of the xanthate portion of the polymer may be represented:

s Cs sO4OC %H2S04 SNa n Alkali cellulose xanthate fl 1oO5)n %NazSOs CS2Regenerated cellulose One aspect of the invention relates to theproduction of metallic-appearing regenerated cellulose seals, such asthe aforedescribed bands or secondary closures, by the application tosaid seals of metallic flake such as aluminum flake or bronze flake. Thecoating or casting of regenerated cellulose by conventional techiquescannot be used in processes where metallic flake is applied to theregenerated cellulose as the opacifying or pigmentary agent. The causticused in the regenerated cellulose processes eventually attacks thealuminum flake to modify or destroy its metallic appearance or thesulfides present in the regenerated cellulose produced by the viscoseprocess darkens bronze flake. Further, no known vehicle or adhesive hasheretofore been available for adhering the metallic flake to the wetcellulose tubing. Also, no adhesive is available which swells andshrinks at the same rate as the regenerated cellulose seal shrinks upondrying.

To overcome the foregoing difficulties, we have developed a new processfor the manufacture of tubular wet cellulose seals having a metallicappearance. In this process, wet cellulose tubing is coated withmetallic flake, such as aluminum flake or bronze flake. The metallicflake coating is thereafter encapsulated by applying to the coated orprinted wet cellulose tubing a continuous film of viscose, which issubsequently regenerated to form a regenerated cellulose, continuous,encapsulating outer film. This technique is also applicable toregenerated cellulose pellicle forms other than the tubular form.

To describe our process in greater detail, the regenerated cellulosepellicle prepared by a viscose process is washed, without drying, of allsurface contaminants. The washed pellicle is then preferably, throughnot essentially, dipped for a short period in dilute caustic of astrength preferably in the range of 3% to 15%. After said dip, thesurface moisture is completely removed from the pellicle. The metallicflake, as a dry powder or aqueous slurry or paste, is coated on thepellicle. The metallic powder coating may be printed as a design or acomplete covering coating may be applied, as desired. A viscose solutionis then sprayed, rolled or extruded on the pelliclecovering andencapsulating the metallic powder coating. Immediately following, theviscose-coated pellicle is immersed in an acid solution, such assulfuric acid solution, to regenerate the viscose layer. When theviscose coating is regenerated it becomes tightly bonded to the metallicpowder coated cellulose pellicle-presumably through a bond between thetwo cellulose layers. The acid from the regeneration bath is immediatelywashed out of the regenerated viscose layer with hot water, and thepellicle is trimmed and plasticized.

In the foregoing process the viscose used to form the gel pellicle has acontent of 6.58.5% cellulose and 5.5- 7% caustic. The acid regenerationbath will contain between 3-l2% sulfuric acid or equivalent amount ofother strong inorganic acid. The dipping of the tubing in the dilute,aqueous caustic solution need only be of short duration. A 3-30 seconddip is ordinarily adequate.

The primary purpose of the dip treatment in aqueous caustic is toimprove the bond between the viscose coating and the regeneratedcellulose pellicle, between which the metallic flake is encapsulated.

The viscose used to provide the outer, regenerated cellulose film willcontain approximately -10% cellulose, approximately 5-12% caustic andhas a salt index greater than 0.25. The period between application ofthe viscose to the cellulose pellicle and the immersion of theviscosecoated pellicle in the acidic regeneration bath should be only afew seconds to avoid attacking of the metallic flake-particularly whenaluminum flake is employed and preferably will not exceed 10 seconds inthe case of aluminum flake. With metallic flakes which are not soquickly attacked by caustic, longer periods may be employed withoutdetriment to the final results. The regenerating bath for the outerviscose film contains approximately 3-10% sulfuric acid and 30% sodiumsulfate. Ammonium sulfate or potassium sulfate may be substituted forsodium sulfate, although the latter is preferred.

In a further aspect of our invention, the previously described techniquemay be employed with opacifyiug or coloring particles other thanmetallic flake or powder. Instead of encapsulating the metallic flake orpowder between the gel regenerated cellulose layer applied thereto,pigmentary or opacifyiug bodies such as organic or inorganic pigmentsmay be so encapsulated to provide a protective cover or coating oversaid bodies and/ or to securely adhere said bodies on the pellicle.

The foregoing process, wherein the metallic flake, metallic powder,organic pigment or inorganic pigment is applied to the original gelregenerated cellulose pellicle, may be modified to produce further newand novel embodiments of the gel regenerated cellulose articles hereindescribed. In this modification, the gel regenerated cellulose pellicleis first coated or sprayed to give a thin film of transparent viscose ofthe type applied as the encapsulating coating in the previouslydescribed embodiments. The film thickness is approximately0.0005"0.002", optimally about 0.001". To this viscose film is applied,as by spraying or other technique, finely-divided opacifyiug or coloringbodies. This process is particularly useful in the application to thegel regenerated viscose pellicle of finelydivicled flakes of metallicappearance, known in the trade as glitters. Glitters are well knowndecorative articles in the packaging and printing industries and aresmall rectangular, usually square, flakes of plastic film, such aspolyethylene terephthalate, with a metallized aluminum coating. Themetallized aluminum surfaces are covered by a coating of clear orcolored lacquer to provide glitters in a Wide variety of colors. Thedimensions of typical glitter flakes commercially marketed are 0.01" to0.015" square with a thickness of 0.0005 to 0.001. This description ofone type of glitter flakes is illustrative only because glitter flakesof other shapes and/ or dimensions can be used in accordance with theprocess herein described.

Following the application of the thin, transparent film to the gelregenerated cellulose pellicle and the application on said film ofpigmentary or opacifying bodies, a coating of clear viscose is applied,e.g., by spraying, over the opacifyiug or pigmentary bodies toencapsulate said bodies between two films of viscose. Thereafter, theviscose of both films is regenerated by a brief dip in a 3-10% sulfuricacid bath which may contain l5-30%of sodium, potassium or ammoniumsulfate. With opacifying or pigmentary bodies which are not readilyattacked by caustic in the viscose, the elapsed time between theapplication of said bodies on the first viscose film and theregeneration of the viscose of both films is not of critical magnitude.However, where the body is a material readily attacked by caustic, suchas aluminum flake or powder, the elapsed time should not exceed about 1015 seconds to minimize attack on the bodies by the caustic of theviscose. On the other hand, materials which are attacked readily bycaustic, can be precoated with clear or colored lacquers or otherprotective coatings to render them harmless or more resistant to attackby caustic.

Another novel effect in the process wherein the pigmentary or opacifyiugbodies are encapsulated between two, thin viscose films is produced byprinting, rather than spraying, on the gel regenerated cellulosepellicle the viscose film. The printed viscose film may cover all oronly a portion of the gel pellicle. The glitters thereupon are sprayedon the viscose print and thereby adhered to the printed portion of thegel pellicle. Thereafter, a film of viscose is applied over the glittersand the viscose of both films is regenerated in the above-describedmanner.

A still further novel effect in the process where the pigmentary oropacifyiug bodies are encapsulated between two, thin viscose films onthe gel regenerated cellulose pellicles is produced by applying to adie-printed gel regenerated cellulose pellicle a quantity sufiicientonly to give a light coverage over the viscose-coated area of glittersor other opaque, small bodies of the type heretofore described, wherebya speckled appearance results. In this process, the gel regeneratedcellulose pellicle is printed by the conventional azo process presentlypracticed with gel regenerated cellulose tubing or other pellicle form.The azo-printing may cover the entire pellicle surface to provide acompletely opaque pellicle. Alternatively, the azo-printing may coveronly a portion of the pellicle to give a design wherein some portionsare colored and opaque whereas other portions remain clear andtransparent. Words, designs, symbols and the like may be printed on theazo-printed portions and/or transparent portions.

The printed pellicle is washed free of all contaminants before applyingthereon,'by spraying, printing, or the like, a film of clear viscose ofa thickness of about 0.0005" to 0.003. Glitters or other opaque bodiesare sprayed on the thin viscose film in a quantity sufiicient to give aspeckled appearance. A film of clear viscose is then applied over thespeckled portion to cover and bond the speckles to the gel pellicle. Theviscose of both films is regenerated in an acid bath by the previouslydescribed technique.

When the encapsulated opacifying bodies are particles of metallic flakesuch as aluminum flake, a good technique for producing a shiny, metallicfoil-appearance on the regenerated cellulose pellicle is by applying onthe gel regenerated cellulose either flattened metallic flake havingessentially flat upper and lower surfaces or metallic flake particleswhich are in essentially parallel orientation. The orientation of theparticles may be done during the process of transferring the metallicflake particles to the printing die, from which they are applied on theregenerated cellulose pellicle in essentially parallel orientation.

The previous description of the generic aspects and concepts of ourinvention as well as some embodiments thereof are further illustrated inthe drawing wherein:

FIG. 1 is a perspective view of a gel regenerated cellulose pellicle inopen-ended, flattened tubular form with two longitudinal stripes ofopaque, finely-divided particles encapsulated on said pellicle by aregenerated cellulose film;

FIG. 2 is a magnified, cross-sectional View of the pellicle across onestripe, taken on section 2-2 of FIG. 1;

FIG. 3 is a broken, side elevation of the neck of a bottle with a dry,tubular regenerated cellulose pellicle with encapsulated metallic flakesand tightly shrunken on the neck and about a portion of the bottleclosure;

FIG. 4 is an enlarged cross-sectional view of the bottle neck taken onsection 44 of FIG. 3;

FIG. 5 is a perspective view of another embodiment of a printed gelregenerated cellulose pellicle in flattened, open-ended, tubular formwith glitters thereon;

FIG. 6 is a magnified, cross-sectional view of a segment of the pellicleof FIG. 5, taken on section 6-6 thereof;

FIG. 7 is a greatly magnified view of a regenerated cellulose pellicle,in dry or gel form, with oriented particles of metallic flakeencapsulated thereon by another film of regenerated viscose, and

FIG. 8 is a segmental view of a gel regenerated cellulose pelliclehaving bronze or aluminum flake printed on said pellicle andencapsulated by an outer film of regenerated viscose.

The open-ended, tubular pellicle of FIG. 1 comprises a tubularregenerated cellulose body 1 in gel form. The tubular pellicle may alsobe essentially flattened because this form permits easy transportationof the pellicle in its gel form. A portion of the clear, transparentpellicle 1 has on the outer surface two stripes 2 of metallic flake,e.g., aluminum flake or bronze flake, running longitudinally from edgeto edge. These stripes are opaque and have a shiny, metallic appearance.The remaining portions 3 of the tubular pellicle are transparent.

The encapsulation of the metallic flake particles on the gel regeneratedcellulose comprising the pellicles 1 is shown in FIG. 2, wherein theouter surface of the gel regenerated cellulose film 4 is covered in partby a stripe of small particles 5 of aluminum or bronze flake. Themetallic flake particles 5 are encapsulated between the gel regeneratedcellulose film 4 and an overlying stripe, preferably of slightly widerdimension than the stripe 6 of the metallic flake, of regeneratedviscose.

In FIG. 3, there is illustrated one use of the gel regenerated cellulosepellicles of the instant invention. A bottle 10 having neck 11 withstopper 12 inserted in the opening of said neck has a tubular, dryregenerated cellulose pellicle shrunken in tight fit about the neck 11and a portion of the cap 12. The shiny appearance of the tubularpellicle 13 is provided by metallic flake encapsulated upon the entireouter surface of said pellicle.

As shown in the cross-sectional view of FIG. 4, the

neck 11 of the bottle 10 has tightly shrunken thereabout the tubularpellicle 13 comprising a body of dry, regenerated cellulose 14 whoseouter surface is covered with small particles 15 of metallic flake. Theparticles 15 of metallic flake are encapsulated on the film 14 by anoverlying layer 15 of regenerated viscose having a thickness in theorder of 00005-0002 inch.

Another novel eflect of the instant invention is shown in FIG. 5 whereina gel regenerated cellulose pellicle 20, illustrated in flattenedtubular form, has printed thereon a legend 21 by the azo printingprocess. The outer surface of the tubular pellicle 20 is covered withsmall glitters 22, previously described, in a speckled arrangement.

From FIG. 6 it is seen that the outer surface of the gel regeneratedcellulose film 23 of the pellicle 20 has adhered thereon a thin film ofregenerated viscose 24, to which, in turn, are adhered the glitters 22.These glitters are then encapsulated by an overlying film of regeneratedviscose 25 which is bonded and probably is an integral part of theregenerated film Z4.

FIG. 7 is a highly magnified view of a regenerated cellulose pellicle30, shown only in segment thereof, wherein metallic flake isencapsulated thereon by any of the previously described techniques. Inthis embodiment, the metallic flake particles 31 are arranged inessentially parallel orientation.

In FIG. 8, a legend 32 is printed with bronze or aluminum flake on thegel regenerated pellicle 33. The legend is encapsulated by a coveringfilm of gel regenerated viscose.

The gel regenerated cellulose pellicles heretofore described contain atleast 50% by weight of water. They are maintained in this moist stateuntil they are applied over a bottle neck or the like. Upon drying, thepellicles shrink to yield the tight fitting closures of the typepreviously described. In general, these gel regenerated cellulosepellicles contain about 65-80% water.

Example 1 In one specific, illustrative embodiment of our invention, atubular gel regenerated cellulose pellicle containing about 75% byweight water is drawn from the end of an extrusion machine and is washedwith water to remove all water-soluble contaminants. This washing stepmay be done by submerging the tubing in a washing tank or by sprayingthe tubular pellicle.

The washed tubing is then dipped for approximately 5 seconds in anaqueous solution of 10% by weight sodium hydroxide. The surface moistureon the tubing is then removed and dry, aluminum flake powder is appliedto the outer surface of the tubing with a printing die. The printing maycover either the entire outer surface of the pellicle to give a completecoating of metallic flake, or a design legend or other indicia may beprinted on only a portion thereof. The gel regenerated Viscose tube maybe clear or may have a complete or partial coating of pigmentarycoloring bodies applied by the conventional azo process. Instead ofapplying the aluminum or bronze flake of the dry powder by a printingdie the metallic flake may be slurried in water and sprayed or cast onthe outer surface of the gel regenerated cellulose tubing.

Immediately following the coating of the gel regenerated cellulosetubing with the metallic flake, a thin viscose layer in the order of0.001 is sprayed on the tubing to cover and encapsulate the metallicflake thereon. The sprayed tubing is thereafter immediately submerged insulfuric acid solution where the sprayed viscose layer is regeneratedand bonded to the tubing. The acid is removed from the tubing by washingin hot water. It is important in the case of aluminum flake, which isreadily attacked by caustic, to quickly neutralize the caustic in thethin, sprayed viscose film before a reaction between the aluminum flakeand the caustic is initiated.

The viscose used to form the encapsulating film contains about 7.5%cellulose, 6.5% caustic and has a salt index of about 0.35. The acidregenerating bath for regenerating the viscose film containsapproximately sulfuric acid and 20% sodium sulfate. The elapsed timebetween spraying of the viscose on a given point of the tubing and thesubmergence of that point of the tubing in the regenerating bath isapproximately 5 seconds.

Example 2 In another illustrative, specific embodiment of our invention,the regenerated cellulose tubing in gel form, as previously described,is first coated with a thin layer of approximately 0.001" of viscosecontaining 7.5% cellulose, 6.5% caustic and having a salt index of about0.35 by spraying said viscose on said tubing. Glitters are then sprayedon the wet viscose film to give a speckled pattern like that illustratedin FIG. 5. The glitters are small flakes which are approximately 0.01 to0.15" square and having thicknesses in the range of about 0.005 to0.001. These flakes are a plastic film of polyethylene terephthalatehaving a metallized aluminum coating. The metallized aluminum surface iscovered by a clear lacquer when a silvery appearance is desired or bycolored lacquers to produce the desired color.

After spraying the glitters on the viscose film, to which the glittersadhere, a second or covering coating of viscose of the same chemicalcharacter as the first applied layer of viscose is applied as byspraying over the glitters. The applied viscose films then areregenerated in the manner previously described in Example 1. If desired,the first coating of viscose applied to the gel regenerated cellulosetubing may be printed rather than sprayed on said tubing. In this casethe glitters adhere essentially only to the viscose printed surface ofthe cellulose tubing. The outer viscose layer, however, is preferablysprayed over the area covered by the glitters in order to assureencapsulation of the glitters.

The foregoing description and specific embodiments of our inventionillustrate the wide varieties of processes for producing variouspatterns and appearances with gel regenerated cellulose pellicles. Manynew and novel effects are producible in accordance with the principlesherein disclosed, and our invention contemplates many embodiments inaddition to the specific embodiments herein disclosed.

The invention is hereby claimed as follows:

1. A process for producing an attractive gel regenerated cellulosearticle which comprises applying on a side of a gel regeneratedcellulose pellicle finely-divided, opaque particles, covering the areaof said pellicle on which said particles are applied with a viscose filmand covering said particle with said viscose film, and then regeneratingsaid viscose film covering said particles in an acid bath to therebyencapsulate said particles on said pellicle under the regeneratedviscose film.

2. A process for producing an attractive gel regenerated cellulosearticle which comprises applying directly on a surface of a gelregenerated cellulose pellicle finelydivided, metallic particles,covering the area of said pellicle on which said particles are appliedwith a viscose film and covering said particles with said viscose film,and immediately regenerating said viscose film covering said particlesin an acid regenerating bath to thereby encapsulate said particles onsaid pellicle under the regenerated viscose film.

3. The process of claim 2 wherein said metallic particles are aluminumflakes.

4. The process of claim 2 wherein said metallic particles are bronzeflakes.

5. The process of claim 2 wherein said metallic particles are aluminumflakes, and said aluminum flakes are arranged in essentially parallelorientation when they are applied to said pellicle.

6. The process of claim 5 wherein said aluminum flakes are flattenedaluminum particles which have essentially flat upper and lower surfaces.

7. The process of claim 1 wherein said pellicle is dipped in 315%caustic prior to applying said particles.

8. A process for producing an attractive gel regenerated cellulosearticle which comprises applying directly on a surface of a gelregenerated cellulose pellicle a film of viscose, applyingfinely-divided opaque particles on said film of viscose, applying onsaid film of viscose and over said particles a second film of viscose,and then regenerating said films of viscose in an acid regeneration bathto encapsulate thereby said particles on said pellicle between theregenerated viscose films.

9. The process of claim 8 wherein said particles are small, aluminummetallized flakes coated with a lacquer.

10. The process of claim 9 wherein said flakes are applied to said filmof viscose by depositing said flakes on said film of viscose in aspeckled pattern.

References Cited in the file of this patent UNITED STATES PATENTS2,087,094 McBurney et a1 July 13, 1937 2,125,341 Hall Aug. 2, 19382,182,188 Walter Dec. 5, 1939 2,273,677 Wallach Feb. 17, 1942 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,142,580 July28,, 1964 George H, Holoubek et a1.

It is hereby certified that error appears in the above numbered patentreq'liring oorrectlo'l a and that the said Letters Patent should read ascorrected below. I

Column 2, line 67, for ".(C H OOS) +%Na SO +CS read (C H O Na S'O +CScolumn 3, line 29, for "through" read though column.5, line 32, after"the" insert gel column 7, line 32, for "O, 15" read 0.015

line 33, for "0,005" read 0.0005 m Signed and sealed this 8th day ofDecember 1964 (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A PROCESS FOR PRODUCING AN ATTRACTIVE GEL REGENERATED CELLULOSEARTICLE WHICH COMPRISES APPLYING ON A SIDE OF GEL REGENERATED CELLULOSEPELLICLE FINELY-DIVIDED, OPAQUE PARTICLES, COVERING THE AREA OF SAIDPELLICLE ON WHICH SAID PARTICLES ARE APPLIED WITH A VISCOSE FILM ANDCOVERING SAID PARTICLE WITH SAID VISCOSE FILM, AND THEN REGENERATINGSAID VISCOSE FILM COVERING SAID PARTICLES IN AN ACID BATH TO THEREBYENCAPSULATE SAID PARTICLES ON SAID PELLICLE UNDER THE REGENERATEDVISCOSE FILM.